Some Common Misperceptions about the Date of Pascha/Easter

This essay was originally published in 2016. It has been updated for the current year.

There is a common misperception among Orthodox Christians that the reason why Orthodox Easter (i.e. Pascha) often occurs so much later than Western Christian Easter is because the Orthodox Church abides by the rules for calculating the date of Pascha issued by the 1stEcumenical Council at Nicaea in 325 AD and thus the Orthodox must wait for Passover to be celebrated by the Jewish community before Pascha can occur. Despite this view being held by so many Orthodox Christians as well as being promoted in popular essays written by some Orthodox priests, it is not accurate. The reason why Orthodox Pascha frequently occurs so much later than Easter celebrated by Roman Catholics and Protestants has nothing to do with the Orthodox Church following the Paschal formula of Nicaea and the Western Churches not doing so, nor is it because the Orthodox must wait for Jewish Passover to be celebrated. Rather, Orthodox Pascha frequently occurs later than Western Easter because the Orthodox Church uses inaccurate scientific calculations that rely on the inaccurate Julian Calendar to determine the date of Pascha for each year. Some background information is in order to help explain precisely what the problems are.

Historically, Jesus’ death and resurrection occurred in association with Jewish Passover, although the synoptic gospels (Mk, Matt, Lk) and the Gospel of John contain differences regarding the precise day of Passover at that time. Because of these differences, early Christian churches developed different practices regarding when they were to celebrate Christian Pascha and how the date of Pascha was to be determined. Some ancient Churches celebrated Pascha on the Sunday immediately following Jewish Passover while others emphasized Jesus’ suffering and death on Pascha and thus celebrated the feast on the same day as Jewish Passover, regardless of what day of the week Passover occurred. Christian communities that adhered to either one of these Paschal traditions often relied on their local Jewish communities’ calculations of Passover in order to determine the date of their respective Christian Pascha. Passover is itself a lunar festival marking the beginning of the new year and is to occur annually on the vernal full moon—a date that came to be designated in the Jewish Calendar as the 14th of Nisan (Exod 12:1-6). Ancient Jewish communities faced many challenges in regulating their year by a lunar calendar. Because the Jewish lunar calendar frequently fell out of step with the seasons of a solar year, Jews added an additional month to their calendar every two or three years to correct Passover from occurring out of season. A late decision to add a month to the Jewish calendar and/or difficulties communicating meant that not all Jewish communities were always aware of the extra month. This resulted in some Jewish communities celebrating Passover in different months, while other Jewish communities ended up mistakenly celebrating Passover twice in the same year.

Because of Christian dependence on unreliable Jewish calculations of the vernal full moon for Passover and because of the varying Christian traditions for the date of Pascha’s celebration, the Roman Emperor Constantine convened the 1st Ecumenical Council at Nicaea which attempted to resolve these issues and promote Christian unity by issuing a formula for the calculation of Pascha. The Council at Nicaea determined that Pascha would occur on:

thefirst Sunday | after the first full moon | after the vernal equinox

This Nicene formula solved several practical issues. First, the Church determined that Pascha would not be celebrated on the same day as the vernal full moon which itself is to mark the festival of Jewish Passover. By resolving to celebrate Pascha on the first Sunday after the vernal full moon, Christian Pascha would forever be associated with Jewish Passover without being identified with it, thus maintaining the historical associations of Jesus’ death and resurrection with Passover. Second, by resolving that the Christian celebration of Pascha must occur annually after the vernal equinox, the Church ensured that Pascha would only occur once each solar year. Third, the Nicene formula itself meant that the Church would not be reliant on Jewish calendars for the calculation of Passover (the vernal full moon i.e. 14 Nisan), nor would the Church be obliged to wait for Jewish communities to celebrate Passover before celebrating Christian Pascha. Rather, the Nicene formula ensured that the Christian calculation of Pascha would occur independently of the Jewish reckoning of Passover by instead using the astronomical data of the vernal equinox and the vernal full moon in order to calculate the Sunday of Pascha. This maintained the historical and theological associations between Jewish Passover and Christian Pascha while allowing the Church to ascertain the vernal full moon (i.e., what should be 14 Nisan and hence Passover) without Jewish calendrical problems. Because Alexandria, Egypt was known as a premier center of astronomy in the ancient world, the Church of Alexandria came to assume responsibility for making the scientific calculations used to determine the date of Pascha. Although today many traditionalist Orthodox assert that it is only permissible to use the Julian Calendar to determine Paschal dates by employing the ancient Alexandrian scientific calculations, this is to ignore that the Alexandrians Christians used their own Egyptian calendrical dates to calculate Pascha which were then translated into Julian Calendar dates for other parts of the empire. Moreover, although the Council of Nicaea issued a clear formula for the calculation of Pascha, it did not precisely regulate the technical details, methods, or calendar by which the vernal equinox and the vernal full moon should be determined. Rather, Alexandria assumed greater responsibility for making Paschal calculations because the Church expected that the best scientific means available would be used to determine Paschal dates.

Although the Orthodox Church and the Western Churches both continue to follow the formula of Nicaea for the determination of Pascha/Easter, the differences in their respective dates of celebration stem largely from the use of different calendars (Julian vs. Gregorian) and different methods of scientific calculation so as to ascertain the vernal equinox and the vernal full moon. The Orthodox Church employs a complex mathematical formula for the calculation of Pascha that uses the more inaccurate Julian Calendar (currently 13 days behind the Gregorian Calendar) and a “fixed” Julian Calendar date of March 21st (Gregorian April 3rd) as the date of the vernal equinox, as well as a mathematically calculated approximation of the vernal full moon based on a 19-year lunar cycle (the Metonic Cycle). In other words, the vernal equinox used by the Orthodox Church for its calculation of Pascha is not the actual astronomical vernal equinox, nor is the vernal full moon that Pascha must follow (according to Nicaea) the actual, astronomical vernal full moon. Simply stated, the best available calendar and best available science are no longer being utilized for the calculation of Pascha which results in Orthodox celebrations of Pascha that are frequently out of sync with the astronomical phenomena of the vernal equinox and the vernal full moon and thus often occur later in the spring. However, the Western Churches use the Gregorian calendar (a much more accurate calendar—although not perfect) and a more generally accurate scientific calculation of the vernal equinox and the vernal full moon which results in a calculation of Easter that better corresponds with the actual astronomical phenomena and that is typically more accurate.

In this year of 2018, for example, Western Easter and Orthodox Pascha are to be celebrated one week apart. Western Easter has been calculated to fall on April 1st, whereas Orthodox Pascha has been calculated to fall on April 8th (Julian Calendar March 26th). However, a quick look at the actual astronomical data quickly demonstrates the problems with the current Orthodox calculation of Pascha. According to the U.S. Naval Observatory, the 2018 vernal equinox is to occur on March 20th at 16:15 p.m. Coordinated Universal Time (UTC). It is important to remember that the date and time of the vernal equinox depend on the meridian used for calculation (the position on earth used as the reference point). Therefore, it is generally agreed that Jerusalem should be used as the meridian since it is the historical location of Jesus’ death and resurrection. Thus, the 2018 vernal equinox is to occur in Jerusalem on March 20th at 18:15 p.m. (UTC+2). Moreover, according to the U.S. Naval Observatory, the first full moon after the vernal equinox in 2018 is to occur on March 31st at 12:37 p.m. (UTC), and in Jerusalem on March 31st at 14:37 p.m. (UTC+2). Since the vernal full moon at Jerusalem that is to occur March 31st, 2018 at 14:37 p.m. is a Saturday, this means that Pascha 2018 should be celebrated on the first Sunday afterward, that is the following day, on Sunday, April 1st, precisely the date that Easter is to be celebrated in 2018 by the Western Churches.

According to the complex mathematical formula currently in use by the Orthodox Church for the calculation of Pascha—without reference to actual astronomical phenomena—the vernal full moon for 2018 has been calculated by the Orthodox Church as occurring on April 4th, 2018 (Julian Calendar March 22nd). However, through simple, non-scientific observation a person could look at the astronomical phenomena visible in the sky on April 4th, 2018 to understand that there will not be a full moon on that date. Rather, the moon will actually be in a waning gibbous on April 4th, 2018 with 83% of the moon’s visible disk illuminated. The lack of a full moon on that date will be evident in Jerusalem (as well as in Chicago!). Rather, in those two locations (and throughout Western Europe and North America) the full moon will occur on Saturday, March 31st, 2018.

It was widely understood by ancient Christians that the vernal full moon could not be determined reliably by observation since what sometimes appears to the eye as a full moon may not, in fact, be one. This is one of the reasons why after Nicaea different Churches in communion with one another developed a wide variety of scientific/mathematical calculations over the centuries to determine the vernal full moon needed to arrive at the date of Pascha. However, scientific methods have advanced significantly since the time of antiquity, as has our ability to reliably know the dates of the vernal equinox and the vernal full moon for any given year. In 1920, the Ecumenical Patriarchate of Constantinople raised the issue of all Churches employing a common calendar so that Eastern and Western Churches could celebrate major Christian feast days together throughout each year. Moreover, in 1923 a Pan-Orthodox Congress under the leadership of the Ecumenical Patriarchate advocated using a Revised Julian Calendar (very similar to the Gregorian Calendar) while also returning to the actual astronomical phenomena of the vernal equinox and the vernal full moon for the calculation of Pascha. However, divisive reactions against adoption of a new calendar and new Paschal calculations resulted in a compromise that allowed autocephalous Orthodox Churches to choose the Old Julian Calendar or the New (Revised Julian) Calendar to regulate the ecclesiastical year, but maintained the Old Julian Calendar and the scientific calculations based on it for the determination of Paschal dates.

In light of the many calendrical and scientific advances today, Orthodox Christians must ask themselves if use of the inaccurate Julian Calendar, use of a “fixed” Julian Calendar date of March 21st (Gregorian April 3rd) for the vernal equinox, and use of a mathematically calculated approximation of the vernal full moon are still faithful to the spirit of the 1st Ecumenical Council at Nicaea. Nicaea issued its formula for the calculation of Pascha so that Christians everywhere would celebrate the most important Christian feast together in unity as a common witness to the world. Nicaea did not precisely regulate the technical details, methods, or calendar by which the vernal equinox and the vernal full moon should be determined, but expected the best available science to be used for the calculation of Pascha. The best available science is no longer being used for the calculation of Pascha.

During this 21st century, the Orthodox and Western Churches will share a common celebration of Pascha only 31 times. In subsequent centuries, the common celebration of Pascha will occur much less frequently as errors in the Julian Calendar become more pronounced. This will result in Orthodox Pascha occurring even later in the year and more severely out of relationship with the vernal equinox and vernal full moon. Unless action is taken, the year 2698 will be the final time that Orthodox Pascha and Western Easter will occur on the same day. There may eventually be generations of Christians who are sadly led to believe that Orthodox and Western Christians have never celebrated Pascha/Easter together.

A consultation on Pascha/Easter between representatives of the Orthodox Church and Western Churches within the World Council of Churches in 1997 resulted in an excellent statement on and thoughtful recommendations for a common celebration of Pascha, but unfortunately these recommendations were never implemented. It is time that Orthodox Christians again begin to discuss this important issue of Paschal calculation and celebration while also moving past widespread misperceptions among Orthodox Christians regarding the reasons why Pascha frequently occurs so much later than Western Easter.

To be sure, Western Christians do utilize the formula issued by Nicaea for the calculation of Pascha, while Orthodox Christians do not need to wait for the Jewish celebration of Passover before Orthodox Pascha can occur. Rather, use of a more accurate calendar as well as more accurate scientific calculations by the Orthodox Church are needed for Orthodox Pascha to occur once again each year on the first Sunday after the first full moon, after the vernal equinox—and again together with our Western Christian brothers and sisters.

John Fotopoulos is an Associate Professor of New Testament in the Department of Religious Studies at Saint Mary’s College, Notre Dame, Indiana.

Public Orthodoxy seeks to promote conversation by providing a forum for diverse perspectives on contemporary issues related to Orthodox Christianity. The positions expressed in this essay are solely the author’s and do not represent the views of the editors or the Orthodox Christian Studies Center.